1. Field of the Invention
The present invention relates to a radiographic apparatus and a radiographic method for obtaining a radiation image of an object by irradiation of radiation, and particularly relates to a technology for a method in which the same object is imaged in a plurality of imaging processes.
2. Description of the Related Art
Conventionally, imaging using radiation has been used in various fields, and particularly in the medical field, is one of the most important methods for diagnosis. In recent years, an imaging sensor that collects, as digitized image data, a radiation image obtained by radiography has also been put into practical use, and digitization is underway in the radiography field. In general, the larger type of such imaging sensors predominantly has a size of about 43 cm×43 cm.
When radiography is performed using such an imaging sensor, there are cases where an area larger than the imaging sensor (for example, the whole body or the full lower limb) has to be imaged. In such cases, it is not possible to image the entire area by a single imaging process, so imaging is performed in a plurality of divided imaging processes. An imaging method has been established in which a desired single piece of large image data is obtained by performing composition processing for multiple pieces of image data acquired by each imaging process. Such an imaging method is generally called divided capture, long-length imaging, stitch capture, or the like.
As a document describing the above imaging method, a reference can be made to Japanese Patent Laid-Open No. 2004-105356.
Here, a general example of a divided capture method will be described.
FIG. 1 is a diagram showing an example in which an image of the full lower limb is acquired from three divided images. First, before performing imaging, the position of an imaging sensor and the swing angle of a tube that generates radiation are adjusted, and preparation for imaging for the first image is performed. In this example, the position of the imaging sensor and the swing angle of the tube during each imaging process are assumed to be determined prior to the positional adjustment.
After performing the positional adjustment, a radiation irradiation switch is depressed by an operator, and the first divided image is imaged. Upon completion of the imaging of the first divided image, the position of the imaging sensor and the swing angle of the tube are automatically adjusted as preparation for imaging of the second image. At this time, the operator continues depressing the radiation irradiation switch. Then, after performing the positional adjustment, the second divided image is imaged. Thereafter, imaging is completed up to the third image by the same operation, and finally the operator depresses the irradiation switch, whereby the series of divided capture is completed.
After performing such divided capture, the acquired three pieces of divided image data are composed by image processing, thus obtaining a single desired composite image. Then, the composite image obtained is put to use in diagnosis, for example, by being displayed or printed.
However, when divided images are obtained in the above-described manner, there have been situations where imaging cannot be completed normally up to the third image if the object moves during imaging, or if the operator releases the irradiation switch. When such a situation occurs, it has been hitherto common to stop all the imaging processes once, and perform imaging again from the first image. Accordingly, it has cost twice the labor for the operator to perform imaging again from the first image, and this has also caused an object to undergo unnecessary exposure to radiation. The present invention provides a technology that enables the operator to designate whether or not to continue imaging if divided capture has been interrupted in a radiographic apparatus.